Following Indigo Snake Movements across the Lake Wales Ridge at the Archbold Biological Station

It was a pleasant, sunny morning in late January when my field technician, Zach Forsburg, and I set out to locate “Shane,” one of our radio telemetered eastern indigo snakes. We were on the Archbold Biological Station in Highlands County, Florida, where the Orianne Society is conducting a study on eastern indigo snakes. Shane was the first indigo to locate that day so Zach and I drove across the station’s sandy fire lanes to the location where Zach had last picked up the signal from Shane’s radio transmitter. We could still hear the pulsing “beeps” from Shane’s transmitter, telling us that Shane was close enough to proceed on foot. Shane’s transmitter was temperature sensitive, meaning the frequency of those “beeps” changed as his body temperature changed, allowing us to tell if Shane was warm and on the surface or cold and underground. This morning he was on the surface. This was good news because it had been over a month since we caught Shane and we wanted to check on him. I followed Zach through the palmetto and scrub oak as he used an antenna to follow the transmitter signal. We must be close now, Zach observed, referring to the increasing volume of the signal. Sure enough, not a few moments later we spotted a long, black shape lying near the entrance of a small, inactive gopher tortoise burrow. After a quick grab, we had Shane in hand. He was a beautiful specimen, over six feet long, with a strong red coloration along his lower jaw. He looked to be in excellent condition so we released him back into his tortoise burrow.

Shane’s involvement in this study began in mid December 2010. He was seen basking across a fire lane running through some scrub at the edge of the station and was captured after a short but brisk chase. After being measured and weighed, he was transported to the Small Animal Hospital at the University of Florida in Gainesville where he received a surgically implanted radio transmitter and micro temperature data logger to record his body temperature. Shane was released January 2, and Zach then began following his movements. Shane immediately began moving, travelling in a zigzag pattern onto some adjacent Florida Fish and Wildlife Conservation Commission land and covering about two-tenths of a mile every three days. This pattern continued until about mid January when he settled down into a small, inactive gopher tortoise burrow for two weeks. Like most snakes, indigo snakes will often find a sheltered location to prepare for ecdysis, the process of shedding their skin, and this is what Shane appeared to be doing. After leaving behind a fully intact shed skin, Shane resumed his movements by moving three-quarters of a mile in three days back onto the station. He continued zigzagging through some flatwoods before settling down in a tortoise burrow for another two weeks. Early March found him back in scrub habitat on state land after moving 4.6 miles since his release!

Shane is one of seven eastern indigo snakes that have been captured on the Archbold Biological Station as part of a study on indigo snake ecology in south-central Florida being conducted by The Orianne Society in partnership with the Archbold Biological Station. This is a multifaceted study looking at indigo snake movement patterns, habitat use, and thermal ecology. However, the driving question behind this study is how do indigo snakes in peninsular Florida respond to habitat fragmentation? Indigo snakes are widespread throughout peninsular Florida, which is considered a stronghold for this species, yet urbanization, development, and road construction continues to fragment remaining natural habitats. Because indigo snakes are large, very active snakes, habitat fragmentation can adversely affect them by breaking their habitat into smaller pieces and increasing road or human-caused mortality. However, the answer to our question may be complex because indigo snakes in peninsular Florida occur in a variety of habitats and are often found in disturbed habitats like suburban developments, citrus groves, or cattle ranches. Studying snakes on the Archbold Biological Station allows us to compare our results to those from snakes in more intact landscapes. We hope that this study will help us better understand the ecology of indigo snakes in these fragmented landscapes.